android SD卡读写操作（以txt文本为例）

1， 首先对manifest注册SD卡读写权限

      要说明一下，我这里没有用MainActivity.class作为软件入口

AndroidManifest.xml 
 1 <?xml version="1.0" encoding="utf-8"?>
 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
 3     package="com.tes.textsd"
 4     android:versionCode="1"
 5     android:versionName="1.0" >
 6 
 7     <uses-sdk
 8         android:minSdkVersion="8"
 9         android:targetSdkVersion="16" />
10     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
11     <application
12         android:allowBackup="true"
13         android:icon="@drawable/ic_launcher"
14         android:label="@string/app_name"
15         android:theme="@style/AppTheme" >
16         <activity
17             android:name="com.tes.textsd.FileOperateActivity"
18             android:label="@string/app_name" >
19             <intent-filter>
20                 <action android:name="android.intent.action.MAIN" />
21 
22                 <category android:name="android.intent.category.LAUNCHER" />
23             </intent-filter>
24         </activity>
25     </application>
26 
27 </manifest>

2,  创建一个对SD卡中文件读写的类

FileHelper.java 
  1 /**
  2  * @Title: FileHelper.java 
  3  * @Package com.tes.textsd 
  4  * @Description: TODO(用一句话描述该文件做什么) 
  5  * @author Alex.Z   
  6  * @date 2013-2-26 下午5:45:40 
  7  * @version V1.0
  8  */
  9 package com.tes.textsd;
 10 
 11 import java.io.DataOutputStream;
 12 import java.io.File; 
 13 import java.io.FileOutputStream;
 14 import java.io.FileWriter;
 15 
 16 import java.io.FileInputStream; 
 17 
 18 import java.io.FileNotFoundException; 
 19 
 20 import java.io.IOException; 
 21 
 22  
 23 
 24 import android.content.Context; 
 25 
 26 import android.os.Environment; 
 27 
 28  
 29 
 30 public class FileHelper { 
 31 
 32  
 33 
 34     private Context context; 
 35 
 36     /** SD卡是否存在**/ 
 37 
 38     private boolean hasSD = false; 
 39 
 40     /** SD卡的路径**/ 
 41 
 42     private String SDPATH; 
 43 
 44     /** 当前程序包的路径**/ 
 45 
 46     private String FILESPATH; 
 47 
 48  
 49 
 50     public FileHelper(Context context) { 
 51 
 52         this.context = context; 
 53 
 54         hasSD = Environment.getExternalStorageState().equals( 
 55 
 56                 android.os.Environment.MEDIA_MOUNTED); 
 57 
 58         SDPATH = Environment.getExternalStorageDirectory().getPath(); 
 59 
 60         FILESPATH = this.context.getFilesDir().getPath(); 
 61 
 62     } 
 63 
 64  
 65 
 66     /**
 67 
 68      * 在SD卡上创建文件
 69 
 70      * 
 71 
 72      * @throws IOException
 73 
 74      */ 
 75 
 76     public File createSDFile(String fileName) throws IOException { 
 77 
 78         File file = new File(SDPATH + "//" + fileName); 
 79 
 80         if (!file.exists()) { 
 81 
 82             file.createNewFile(); 
 83 
 84         } 
 85 
 86         return file; 
 87 
 88     } 
 89 
 90  
 91 
 92     /**
 93 
 94      * 删除SD卡上的文件
 95 
 96      * 
 97 
 98      * @param fileName
 99 
100      */ 
101 
102     public boolean deleteSDFile(String fileName) { 
103 
104         File file = new File(SDPATH + "//" + fileName); 
105 
106         if (file == null || !file.exists() || file.isDirectory()) 
107 
108             return false; 
109 
110         return file.delete(); 
111 
112     } 
113     /**
114      * 写入内容到SD卡中的txt文本中
115      * str为内容   
116      */
117     
118     public void writeSDFile(String str,String fileName)
119     {
120         try { 
121             FileWriter fw = new FileWriter(SDPATH + "//" + fileName); 
122             File f = new File(SDPATH + "//" + fileName); 
123             fw.write(str); 
124 
125             FileOutputStream os = new FileOutputStream(f); 
126             DataOutputStream out = new DataOutputStream(os); 
127             out.writeShort(2); 
128             out.writeUTF(""); 
129             System.out.println(out); 
130             fw.flush(); 
131             fw.close(); 
132             System.out.println(fw); 
133             } catch (Exception e) { 
134             } 
135     }
136 
137     /**
138 
139      * 读取SD卡中文本文件
140 
141      * 
142 
143      * @param fileName
144 
145      * @return
146 
147      */ 
148 
149     public String readSDFile(String fileName) { 
150 
151         StringBuffer sb = new StringBuffer(); 
152 
153         File file = new File(SDPATH + "//" + fileName); 
154 
155         try { 
156 
157             FileInputStream fis = new FileInputStream(file); 
158 
159             int c; 
160 
161             while ((c = fis.read()) != -1) { 
162 
163                 sb.append((char) c); 
164 
165             } 
166 
167             fis.close(); 
168 
169         } catch (FileNotFoundException e) { 
170 
171             e.printStackTrace(); 
172 
173         } catch (IOException e) { 
174 
175             e.printStackTrace(); 
176 
177         } 
178 
179         return sb.toString(); 
180 
181     } 
182 
183  
184 
185     public String getFILESPATH() { 
186 
187         return FILESPATH; 
188 
189     } 
190 
191  
192 
193     public String getSDPATH() { 
194 
195         return SDPATH; 
196 
197     } 
198 
199  
200 
201     public boolean hasSD() { 
202 
203         return hasSD; 
204 
205     } 
206 
207 }

3, 写一个用于检测读写功能的的布局

main.xml 
 1 <?xml version="1.0" encoding="utf-8"?> 
 2 
 3 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 4 
 5     android:layout_width="fill_parent" 
 6 
 7     android:layout_height="fill_parent" 
 8 
 9     android:orientation="vertical" > 
10 
11  
12 
13     <TextView 
14 
15         android:id="@+id/hasSDTextView" 
16 
17         android:layout_width="fill_parent" 
18 
19         android:layout_height="wrap_content" 
20 
21         android:text="hello" /> 
22 
23  
24 
25     <TextView 
26 
27         android:id="@+id/SDPathTextView" 
28 
29         android:layout_width="fill_parent" 
30 
31         android:layout_height="wrap_content" 
32 
33         android:text="hello" /> 
34 
35  
36 
37     <TextView 
38 
39         android:id="@+id/FILESpathTextView" 
40 
41         android:layout_width="fill_parent" 
42 
43         android:layout_height="wrap_content" 
44 
45         android:text="hello" /> 
46 
47  
48 
49     <TextView 
50 
51         android:id="@+id/createFileTextView" 
52 
53         android:layout_width="fill_parent" 
54 
55         android:layout_height="wrap_content" 
56 
57         android:text="false" /> 
58 
59      
60 
61     <TextView 
62 
63         android:id="@+id/readFileTextView" 
64 
65         android:layout_width="fill_parent" 
66 
67         android:layout_height="wrap_content" 
68 
69         android:text="false" /> 
70 
71      
72 
73     <TextView 
74 
75         android:id="@+id/deleteFileTextView" 
76 
77         android:layout_width="fill_parent" 
78 
79         android:layout_height="wrap_content" 
80 
81         android:text="false" /> 
82 
83  
84 
85 </LinearLayout>

4, 就是UI的类了

FileOperateActivity.class 
  1 /**
  2  * @Title: FileOperateActivity.java 
  3  * @Package com.tes.textsd 
  4  * @Description: TODO(用一句话描述该文件做什么) 
  5  * @author Alex.Z   
  6  * @date 2013-2-26 下午5:47:28 
  7  * @version V1.0
  8  */
  9 package com.tes.textsd;
 10 
 11 import java.io.IOException; 
 12 
 13 
 14 
 15 import android.app.Activity; 
 16 
 17 import android.os.Bundle; 
 18 
 19 import android.widget.TextView; 
 20 
 21  
 22 
 23 public class FileOperateActivity extends Activity { 
 24 
 25  
 26 
 27     private TextView hasSDTextView; 
 28 
 29     private TextView SDPathTextView; 
 30 
 31     private TextView FILESpathTextView; 
 32 
 33     private TextView createFileTextView; 
 34 
 35     private TextView readFileTextView; 
 36 
 37     private TextView deleteFileTextView; 
 38 
 39     private FileHelper helper; 
 40 
 41  
 42 
 43     @Override 
 44 
 45     public void onCreate(Bundle savedInstanceState) { 
 46 
 47         super.onCreate(savedInstanceState); 
 48 
 49         setContentView(R.layout.main); 
 50 
 51  
 52 
 53         hasSDTextView = (TextView) findViewById(R.id.hasSDTextView); 
 54 
 55         SDPathTextView = (TextView) findViewById(R.id.SDPathTextView); 
 56 
 57         FILESpathTextView = (TextView) findViewById(R.id.FILESpathTextView); 
 58 
 59         createFileTextView = (TextView) findViewById(R.id.createFileTextView); 
 60 
 61         readFileTextView = (TextView) findViewById(R.id.readFileTextView); 
 62 
 63         deleteFileTextView = (TextView) findViewById(R.id.deleteFileTextView); 
 64 
 65  
 66 
 67         helper = new FileHelper(getApplicationContext()); 
 68 
 69  
 70 
 71         hasSDTextView.setText("SD卡是否存在:" + helper.hasSD()); 
 72 
 73         SDPathTextView.setText("SD卡路径:" + helper.getSDPATH()); 
 74 
 75         FILESpathTextView.setText("包路径:" + helper.getFILESPATH()); 
 76 
 77  
 78 
 79         try { 
 80 
 81             createFileTextView.setText("创建文件：" 
 82 
 83                     + helper.createSDFile("test.txt").getAbsolutePath()); 
 84 
 85         } catch (IOException e) { 
 86 
 87             e.printStackTrace(); 
 88 
 89         } 
 90 
 91  
 92 
 93         deleteFileTextView.setText("删除文件是否成功:" 
 94 
 95                 + helper.deleteSDFile("xx.txt")); 
 96 
 97         helper.writeSDFile("1213212", "test.txt");
 98 
 99         readFileTextView.setText("读取文件:" + helper.readSDFile("test.txt")); 
100 
101     } 
102 
103 }

看看运行的效果：

posted on 2013-02-27 10:11  alexfqyp  阅读(2766)  评论(0)    收藏  举报

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